A fully degradable polymer composite material for tableware and its preparation method

Abstract

The present invention provides a fully degradable polymer composite material for tableware and a preparation method thereof, belonging to the technical field of polymer materials. The present invention uses a specific proportion of amylose corn starch, hydrophobically modified corn starch, acetylated cassava distarch phosphate, polylactic acid-polybutylene succinate interpenetrating network structure material, a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, stearic acid-modified micron titanium dioxide, chitosan quaternary ammonium salt, a composite plasticizer, a composite thermal stabilizer and stearic acid for compounding to obtain a fully degradable polymer composite material. The composite material has controllable good biodegradability, excellent mechanical properties, enhanced thermal stability, improved processing performance, easier and more uniform mixing of the components, convenient material molding and processing, and improved production efficiency and product quality.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a fully degradable polymer composite material for tableware and a preparation method thereof. Background Art

[0002] Over the past few decades, traditional plastic tableware has been widely used in the catering industry due to its low cost, easy production, and stable performance. However, with the rise of global environmental awareness and the growing severity of plastic pollution, the environmental damage caused by traditional plastic tableware has gradually become a focus of social attention.

[0003] Traditional plastic tableware is primarily made of non-degradable polymers such as polyethylene (PE), polypropylene (PP), and polystyrene (PS). These materials are difficult to decompose in the natural environment, and their degradation cycle often takes hundreds or even thousands of years. When large amounts of discarded plastic tableware are carelessly discarded, they not only cause "white pollution," damaging soil structure, affecting soil permeability and water retention, hindering the growth and development of crop roots, and leading to reduced crop yields, but also pose a serious threat to aquatic ecosystems. Plastic waste floats in rivers, lakes, and oceans, and is accidentally ingested by aquatic organisms, causing intestinal blockages, malnutrition, and even death, disrupting the balance of the entire aquatic ecosystem. Furthermore, the production of traditional plastic tableware consumes large amounts of non-renewable resources such as petroleum. With the increasing depletion of petroleum resources, finding sustainable alternative materials has become urgent.

[0004] To address the environmental issues associated with traditional plastic tableware, biodegradable materials have emerged. These materials, under specific environmental conditions such as microorganisms, light, and moisture, undergo chemical structural changes over a period of time, ultimately breaking down into small molecules and returning to the natural environment. Currently, biodegradable materials used in tableware primarily include biodegradable and photodegradable materials.

[0005] Biodegradable materials utilize the metabolic activity of microorganisms to break down materials into harmless substances such as carbon dioxide, water, and biomass. Common biodegradable materials include polylactic acid (PLA), polyhydroxyalkanoates (PHA), and starch-based materials. PLA is produced by fermenting starch or sugars extracted from renewable plant resources (such as corn and sugarcane). It has excellent biocompatibility and can be made into various tableware, such as lunch boxes and plates. However, PLA tableware is brittle and prone to cracking in dry environments. When exposed to hot food or hot water, it may shrink, deform, or even leak. Polyhydroxyalkanoates, a type of polyester synthesized by microorganisms under specific conditions, exhibit excellent biodegradability and biocompatibility, but their high production cost limits their large-scale application. Starch-based materials, made primarily from starch with the addition of other additives, are relatively low-cost, but suffer from poor mechanical properties and water resistance.

[0006] Photodegradable materials are made by adding photosensitizers to plastics, causing them to undergo a photochemical reaction under ultraviolet light, leading to their decomposition. However, the degradation process of photodegradable materials is significantly affected by lighting conditions. Effective degradation is difficult indoors or in environments with insufficient light. Furthermore, incomplete degradation can still produce small molecular fragments, posing potential environmental hazards.

[0007] Therefore, it is necessary to develop more suitable materials to achieve good performance by improving material formula and production process, and to achieve controllable degradation to meet the dual requirements of tableware for performance and environmental protection. Summary of the Invention

[0008] In response to the problems of existing polymer degradable materials for tableware, such as polylactic acid brittle cracking, starch softening, insufficient mechanical strength, poor heat and water resistance, and limited degradation conditions, the present invention provides a fully degradable polymer composite material for tableware and a preparation method thereof. The composite material is compounded with a specific ratio of linear corn starch, hydrophobically modified corn starch, cassava acetylated distarch phosphate, polylactic acid-polybutylene succinate interpenetrating network structure material, a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, stearic acid-modified micronized titanium dioxide, chitosan quaternary ammonium salt, composite plasticizer, composite thermal stabilizer, etc. to obtain a fully degradable polymer composite material with controllable good biodegradability, excellent mechanical properties, enhanced thermal stability, improved processing performance, easier mixing of the components, convenient material molding and processing, and improved production efficiency and product quality. The specific technical solution is as follows:

[0009] A fully biodegradable polymer composite material for tableware comprises the following raw materials in parts by weight: 3 to 5 parts of amylose corn starch, 10 to 15 parts of hydrophobically modified corn starch, 10 to 15 parts of acetylated distarch phosphate of cassava, 30 to 40 parts of polylactic acid-polybutylene succinate interpenetrating network structure material, 8 to 10 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 3 to 5 parts of polycaprolactone, 1 to 2 parts of stearic acid-modified micronized titanium dioxide, 2 to 4 parts of chitosan quaternary ammonium salt, 5 to 8 parts of a composite plasticizer, 3 to 5 parts of a composite thermal stabilizer, and 0.3 to 1 part of stearic acid.

[0010] Among the above raw materials, the preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: uniformly mixing polylactic acid, polybutylene succinate and rosmarinic acid at 80°C to 90°C, then extruding using a twin-screw extruder, air-cooling and drawing, and pelletizing to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0011] In the method for preparing the polylactic acid-polybutylene succinate interpenetrating network structure material, the mass ratio of polylactic acid to polybutylene succinate is (1-1.5):1; the amount of rosmarinic acid used is 3% to 5% of the total mass of the polylactic acid and polybutylene succinate; the extrusion temperature of the twin-screw extruder is 165°C to 180°C, and the screw speed is 250 rpm to 300 rpm. The materials are fully melted and mixed under the high temperature and shearing action of the screw to form an interpenetrating network structure.

[0012] Among the above raw materials, the preparation method of stearic acid modified micron titanium dioxide includes: dissolving stearic acid in ethanol, then adding micron titanium dioxide, ultrasonically dispersing evenly, stirring for reaction, evaporating and recovering ethanol, vacuum drying the solid, and breaking it up to obtain stearic acid modified micron titanium dioxide.

[0013] In the preparation method of the above-mentioned stearic acid-modified micron titanium dioxide, the mass ratio of micron titanium dioxide to stearic acid is 10:(1~1.5); the amount of ethanol used is 100 times to 150 times the mass of stearic acid, and the temperature of ethanol is 60℃~65℃; the stirring reaction time is 1h~2h, and the stirring reaction speed is 300r / min~500r / min; the vacuum drying temperature is 40℃~50℃, and vacuum drying is performed to constant weight.

[0014] Among the above raw materials, the composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxy soybean oil of (3-4):(1-1.5).

[0015] Among the above raw materials, the composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of (2-3):(1-1.5).

[0016] The method for preparing the above-mentioned fully degradable polymer composite material for tableware comprises the following steps:

[0017] S1: uniformly mixing amylose corn starch, hydrophobically modified corn starch, and acetylated cassava distarch phosphate at 70°C to 80°C according to their weight ratios, then adding stearic acid-modified micronized titanium dioxide and uniformly mixing; then adding polylactic acid-polybutylene succinate interpenetrating network structural material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt and uniformly mixing; then adding a composite plasticizer, a composite thermal stabilizer, and stearic acid and uniformly mixing at 60°C to 70°C to obtain a base material;

[0018] S2: adding the base material into a twin-screw extruder for melt blending and extrusion, air cooling and drawing, and pelletizing to obtain pellets of a fully degradable polymer composite material.

[0019] In the above preparation method, amylose corn starch, hydrophobically modified corn starch and acetylated distarch phosphate of cassava are pre-dried; polylactic acid-polybutylene succinate interpenetrating network structural material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt are pre-crushed and dried.

[0020] In the above preparation method, the extrusion temperature of the twin-screw extruder is 160° C. to 170° C., and the screw speed is 250 r / min to 300 r / min.

[0021] The fully degradable polymer composite material for tableware and its preparation method of the present invention have the following beneficial effects:

[0022] 1. Amylose corn starch contains a large number of hydroxyl groups, which can form extensive hydrogen bonds between molecules, giving the material a certain cohesive force, which helps to improve the overall strength and stability of the material. However, amylose corn starch is highly hydrophilic. When used alone, the material easily absorbs moisture, resulting in performance degradation. Hydrophobically modified corn starch significantly improves its hydrophilicity by hydrophobically modifying corn starch while retaining some of the starch's original properties. It can reduce the overall hygroscopicity of the material, improve the material's dimensional stability and water resistance in humid environments, and avoid problems such as softening and reduced strength due to water absorption. Cassava acetylated distarch phosphate has good film-forming properties and flexibility. It can form a continuous film structure inside the material, increase the material's flexibility, and make it less likely to crack when subjected to external forces.

[0023] Amylose corn starch provides the cohesive force and strength basis, which can reduce the water absorption of the composite material to a certain extent. Hydrophobically modified corn starch improves water resistance, and acetylated distarch phosphate of cassava increases flexibility. The three work together to achieve a better balance between strength, flexibility and water resistance of the material, overcoming the limitations of the performance of a single starch material and significantly improving the overall performance.

[0024] II. Preparation of Interpenetrating Networks (IPNs) Using Polylactic Acid (PLA) and Polybutylene Succinate (PBS): PLA has excellent mechanical and processing properties but is relatively brittle; PBS has good flexibility and biodegradability but relatively low strength. Forming these two into an IPN structure achieves complementary performance. Rosmarinic acid contains multiple phenolic hydroxyl groups in its molecular structure, which have strong hydrogen bonding ability. During the preparation of the PLA-PSN IPN, the phenolic hydroxyl groups of rosmarinic acid form numerous hydrogen bonds with carbonyl, hydroxyl, and other groups on the PLA and PBS chains. These hydrogen bonds promote interpenetration and entanglement of the PLA and PBS chains, enabling more uniform mixing of the two polymers and forming a more stable and complete IPN structure. Furthermore, the presence of hydrogen bonds enhances the interactions between the molecular chains, thereby improving the mechanical properties of the material. Furthermore, the thermal stability of the material is enhanced, allowing it to maintain good performance at elevated temperatures, resist high-temperature oxidation, and reduce thermal degradation.

[0025] 3. Polylactic acid-polybutylene succinate interpenetrating network structural material: It combines the high strength and easy processing of PLA with the flexibility and biodegradability of PBS, has good mechanical properties and processing properties, and can meet the requirements of tableware for strength and shape retention during molding and use. Copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV): PHBV is a polymer with excellent biocompatibility and biodegradability. It can be decomposed into small molecules such as water and carbon dioxide by microorganisms in the natural environment. However, PHBV alone is difficult to meet the strength and durability requirements of tableware. The present invention uses the two in a certain proportion. The polylactic acid-polybutylene succinate interpenetrating network structural material provides good mechanical strength and processing properties, ensuring the strength and stability of the tableware during use; PHBV gives the material excellent biodegradability, so that the tableware can be quickly degraded in the natural environment after use, reducing pollution to the environment. The two work synergistically to achieve the dual advantages of performance and environmental protection.

[0026] Fourth, the polycaprolactone (PCL) molecular chain has high flexibility and can play a plasticizing role in composite materials, reducing the interaction force between other polymer molecular chains, so that the overall flexibility of the material is improved, thereby improving the processing performance of the material, making it easier to form during the processing process, and also improving the mechanical properties of the material during use, reducing the risk of fracture due to brittleness. PCL has good compatibility with a variety of polymers and can be mixed with other components in the composite material, including polylactic acid-polybutylene succinate interpenetrating network structure materials, starch substances, etc., at the molecular level. This compatibility can reduce the interfacial tension between the components, promote the uniform dispersion of the components, form a more stable composite material system, avoid performance defects caused by uneven dispersion of components, and thus improve the overall performance of the material.

[0027] 5. Micronized titanium dioxide itself has high hardness and good ultraviolet shielding properties, which can improve the mechanical strength of the material. However, due to its hydrophilic surface, it has poor compatibility with organic polymer materials, is difficult to disperse evenly in the polymer matrix, and is prone to agglomeration. This not only fails to fully exert its role in strengthening and shielding ultraviolet rays, but instead becomes a stress concentration point inside the material, reducing the performance of the material. The present invention uses stearic acid to modify the surface of micronized titanium dioxide. The long-chain alkyl part in the stearic acid molecule has a similar structure to that of organic polymer materials and can produce a good affinity with the polymer matrix. At the same time, the coating of stearic acid introduces hydrophobic groups on the surface of micronized titanium dioxide, greatly improving its compatibility with organic polymer materials. Therefore, the micronized titanium dioxide modified with stearic acid can be more evenly dispersed in the polymer matrix, fully exert its strengthening effect, effectively improve the mechanical properties of the material, and better play its shielding effect against ultraviolet rays.

[0028] 6. Ferric pyrophosphate has excellent thermal stability and oxidation resistance. Under high-temperature conditions, it can capture free radicals generated during material degradation and inhibit the material's oxidative degradation reaction, thereby stabilizing the material's chemical structure and preventing performance degradation due to thermal oxidation, including yellowing and brittleness. In addition to its thermal stabilization properties, zinc stearate also has excellent lubricity. During material processing, zinc stearate can reduce the friction coefficient between the material and processing equipment, as well as between molecules within the material, preventing localized overheating due to frictional heat generation and thus avoiding thermal degradation. Furthermore, the lubricating film formed by zinc stearate in the material can improve the material's fluidity and enhance processing performance.

[0029] Ferric pyrophosphate primarily improves the material's thermal stability by inhibiting oxidative degradation, while zinc stearate ensures thermal stability during processing by reducing friction and improving processing performance. The present invention combines the two components in a specific ratio based on their properties, synergizing them in different aspects to comprehensively improve the material's thermal stability and maintain stable performance during processing and use.

[0030] 7. Tributyl citrate can insert itself between polymer chains, weakening their interactions and increasing their mobility. This significantly improves the material's flexibility and plasticity, making it easier to process and shape, meeting the demands of complex tableware shapes. Epoxidized soybean oil contains epoxy groups in its molecular structure, which interact with polymer chains, further enhancing the material's cohesion and stability. Epoxidized soybean oil also improves the material's water resistance.

[0031] Tributyl citrate is primarily responsible for improving the material's flexibility and plasticity, while epoxidized soybean oil aids in plasticization while enhancing its water resistance and other properties. The combined use of these two ingredients creates a synergistic effect of plasticization and other performance enhancements, resulting in a material that not only exhibits excellent processing properties and flexibility, but also possesses excellent water resistance and other comprehensive properties, meeting the performance requirements of tableware in various usage environments.

[0032] In summary, the use of the fully degradable polymer composite material of the present invention to prepare tableware has controllable and good biodegradability, excellent mechanical properties, enhanced thermal stability, improved processing performance, makes it easier to mix the various components evenly, facilitates the molding and processing of the material, and improves production efficiency and product quality. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to specific implementation cases, but the present invention is not limited to these embodiments.

[0034] Example 1

[0035] A fully biodegradable polymer composite material for tableware comprises the following raw materials in parts by mass: 4 parts of amylose corn starch, 12 parts of hydrophobically modified corn starch, 13 parts of acetylated distarch phosphate of cassava, 35 parts of polylactic acid-polybutylene succinate interpenetrating network structure material, 9 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 4 parts of polycaprolactone, 1.5 parts of stearic acid-modified micronized titanium dioxide, 3 parts of chitosan quaternary ammonium salt, 7 parts of a composite plasticizer, 4 parts of a composite thermal stabilizer, and 0.6 parts of stearic acid.

[0036] The preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: uniformly mixing the polylactic acid, polybutylene succinate and rosmarinic acid at 85° C. according to the mass ratio of polylactic acid to polybutylene succinate of 1.3:1 and the amount of rosmarinic acid of 4% of the total mass of the polylactic acid and polybutylene succinate; then extruding the materials through a twin-screw extruder at an extrusion temperature of 175° C. and a screw speed of 280 r / min; fully melting and mixing the materials under the high temperature and shearing action of the screw to form an interpenetrating network structure; and air-cooling the strips and pelletizing them to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0037] Among them, the preparation method of stearic acid-modified micron titanium dioxide includes: dissolving stearic acid in 62°C ethanol with a mass ratio of micron titanium dioxide to stearic acid of 10:1.3, then adding micron titanium dioxide, uniformly dispersing it by 40KHz ultrasonic dispersion, stirring at 400r / min for 1.5h, evaporating and recovering ethanol, vacuum drying the solid at 45°C to constant weight, and breaking it up to obtain stearic acid-modified micron titanium dioxide.

[0038] The composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxy soybean oil of 3.5:1.2.

[0039] The composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of 2.5:1.2.

[0040] The method for preparing the above-mentioned fully degradable polymer composite material for tableware comprises the following steps:

[0041] The amylose corn starch, hydrophobically modified corn starch and acetylated cassava distarch phosphate were pre-dried at 75°C for 18 hours and set aside; the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt were pre-crushed and pre-dried at 75°C for 18 hours and set aside;

[0042] S1: uniformly mixing amylose corn starch, hydrophobically modified corn starch, and acetylated distarch phosphate of cassava at 75° C. according to parts by mass, then adding stearic acid-modified micronized titanium dioxide and uniformly mixing; then adding polylactic acid-polybutylene succinate interpenetrating network structural material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt and uniformly mixing; then adding a composite plasticizer, a composite thermal stabilizer, and stearic acid, and uniformly mixing at 65° C. to obtain a base material;

[0043] S2: adding the base material into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 165° C. and a screw speed of 280 r / min; air-cooling the strips and pelletizing the strips to obtain pellets of the fully degradable polymer composite material.

[0044] Example 2

[0045] A fully biodegradable polymer composite material for tableware comprises the following raw materials in parts by mass: 3 parts of amylose corn starch, 10 parts of hydrophobically modified corn starch, 10 parts of acetylated distarch phosphate of cassava, 30 parts of polylactic acid-polybutylene succinate interpenetrating network structure material, 8 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 3 parts of polycaprolactone, 1 part of stearic acid-modified micronized titanium dioxide, 2 parts of chitosan quaternary ammonium salt, 5 parts of a composite plasticizer, 3 parts of a composite thermal stabilizer and 0.3 parts of stearic acid.

[0046] The preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: uniformly mixing the polylactic acid, polybutylene succinate and rosmarinic acid at 80°C according to the mass ratio of polylactic acid to polybutylene succinate of 1:1 and the amount of rosmarinic acid of 3% of the total mass of the polylactic acid and polybutylene succinate; then extruding the materials through a twin-screw extruder at an extrusion temperature of 165°C and a screw speed of 250 r / min; fully melting and mixing the materials under the high temperature and shearing action of the screw to form an interpenetrating network structure; and air-cooling the strips and pelletizing them to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0047] Among them, the preparation method of stearic acid modified micron titanium dioxide includes: dissolving stearic acid in 60°C ethanol with a mass ratio of micron titanium dioxide to stearic acid of 10:1, then adding micron titanium dioxide, uniformly dispersing it by 30KHz ultrasonication, stirring at 300r / min for 1h, evaporating and recovering ethanol, vacuum drying the solid at 40°C to constant weight, and breaking it up to obtain stearic acid modified micron titanium dioxide.

[0048] The composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxidized soybean oil of 3:1.

[0049] Among them, the composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of 2:1.

[0050] The method for preparing the above-mentioned fully degradable polymer composite material for tableware comprises the following steps:

[0051] The amylose corn starch, hydrophobically modified corn starch and acetylated cassava distarch phosphate were pre-dried at 70°C for 12 hours and set aside; the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt were pre-crushed and pre-dried at 70°C for 12 hours and set aside;

[0052] S1: uniformly mixing amylose corn starch, hydrophobically modified corn starch, and acetylated distarch phosphate of cassava at 70° C. according to parts by mass, then adding stearic acid-modified micronized titanium dioxide and uniformly mixing; then adding polylactic acid-polybutylene succinate interpenetrating network structural material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt and uniformly mixing; then adding a composite plasticizer, a composite thermal stabilizer, and stearic acid and uniformly mixing at 60° C. to obtain a base material;

[0053] S2: adding the base material into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 160° C. and a screw speed of 250 r / min; air-cooling the strips and pelletizing them to obtain pellets of a fully degradable polymer composite material.

[0054] Example 3

[0055] A fully biodegradable polymer composite material for tableware comprises the following raw materials in parts by mass: 3 parts of amylose corn starch, 15 parts of hydrophobically modified corn starch, 10 parts of acetylated cassava distarch phosphate, 40 parts of polylactic acid-polybutylene succinate interpenetrating network structure material, 8 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 5 parts of polycaprolactone, 1 part of stearic acid-modified micronized titanium dioxide, 4 parts of chitosan quaternary ammonium salt, 5 parts of a composite plasticizer, 5 parts of a composite thermal stabilizer, and 0.3 parts of stearic acid.

[0056] The preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: uniformly mixing the polylactic acid, polybutylene succinate and rosmarinic acid at 90°C according to the mass ratio of polylactic acid to polybutylene succinate of 1.5:1 and the amount of rosmarinic acid of 3% of the total mass of the polylactic acid and polybutylene succinate; then extruding the polylactic acid, polybutylene succinate and rosmarinic acid through a twin-screw extruder at an extrusion temperature of 165°C and a screw speed of 300 r / min; fully melting and mixing the materials under the high temperature and shearing action of the screw to form an interpenetrating network structure; and air-cooling the resulting strips and pelletizing them to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0057] Among them, the preparation method of stearic acid modified micron titanium dioxide includes: dissolving stearic acid in 60°C ethanol with a mass ratio of micron titanium dioxide to stearic acid of 10:1, then adding micron titanium dioxide, uniformly dispersing it by 50KHz ultrasonic dispersion, stirring at 300r / min for 2h, evaporating and recovering ethanol, vacuum drying the solid at 40°C to constant weight, and breaking it up to obtain stearic acid modified micron titanium dioxide.

[0058] The composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxy soybean oil of 4:1.

[0059] Among them, the composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of 3:1.

[0060] The method for preparing the above-mentioned fully degradable polymer composite material for tableware comprises the following steps:

[0061] The amylose corn starch, hydrophobically modified corn starch and acetylated cassava distarch phosphate were pre-dried at 80°C for 12 hours and set aside; the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt were pre-crushed and pre-dried at 80°C for 12 hours and set aside;

[0062] S1: uniformly mixing amylose corn starch, hydrophobically modified corn starch, and acetylated cassava distarch phosphate at 80° C. according to parts by mass, then adding stearic acid-modified micronized titanium dioxide and uniformly mixing; then adding polylactic acid-polybutylene succinate interpenetrating network structural material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt and uniformly mixing; then adding a composite plasticizer, a composite thermal stabilizer, and stearic acid and uniformly mixing at 60° C. to obtain a base material;

[0063] S2: adding the base material into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 170° C. and a screw speed of 250 r / min; air-cooling the strips and pelletizing them to obtain pellets of a fully degradable polymer composite material.

[0064] Example 4

[0065] A fully biodegradable polymer composite material for tableware comprises the following raw materials in parts by mass: 5 parts of amylose corn starch, 15 parts of hydrophobically modified corn starch, 15 parts of acetylated cassava distarch phosphate, 40 parts of polylactic acid-polybutylene succinate interpenetrating network structure material, 10 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 5 parts of polycaprolactone, 2 parts of stearic acid-modified micronized titanium dioxide, 4 parts of chitosan quaternary ammonium salt, 8 parts of a composite plasticizer, 5 parts of a composite thermal stabilizer, and 1 part of stearic acid.

[0066] The preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: uniformly mixing the polylactic acid, polybutylene succinate and rosmarinic acid at 90° C. according to the mass ratio of polylactic acid to polybutylene succinate of 1.5:1 and the amount of rosmarinic acid of 5% of the total mass of the polylactic acid and polybutylene succinate; then extruding the polylactic acid, polybutylene succinate and rosmarinic acid through a twin-screw extruder at an extrusion temperature of 180° C. and a screw speed of 300 r / min; fully melting and mixing the materials under the high temperature and shearing action of the screw to form an interpenetrating network structure; and air-cooling the strips and pelletizing them to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0067] Among them, the preparation method of stearic acid modified micron titanium dioxide includes: dissolving stearic acid in 65°C ethanol with a mass ratio of micron titanium dioxide to stearic acid of 10:1.5, then adding micron titanium dioxide, uniformly dispersing it by 50KHz ultrasonic dispersion, stirring at 500r / min for 2h, evaporating and recovering ethanol, vacuum drying the solid at 50°C to constant weight, and breaking it up to obtain stearic acid modified micron titanium dioxide.

[0068] The composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxidized soybean oil of 4:1.5.

[0069] Among them, the composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of 3:1.5.

[0070] The method for preparing the above-mentioned fully degradable polymer composite material for tableware comprises the following steps:

[0071] The amylose corn starch, hydrophobically modified corn starch and acetylated cassava distarch phosphate were pre-dried at 80°C for 24 hours and set aside; the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt were pre-crushed and pre-dried at 80°C for 24 hours and set aside;

[0072] S1: According to parts by mass, amylose corn starch, hydrophobically modified corn starch and acetylated distarch phosphate of cassava are uniformly mixed at 80°C, and then stearic acid-modified micronized titanium dioxide is added and uniformly mixed; then polylactic acid-polybutylene succinate interpenetrating network structure material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt are added and uniformly mixed; then a composite plasticizer, a composite thermal stabilizer and stearic acid are added and uniformly mixed at 70°C to obtain a base material;

[0073] S2: adding the base material into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 170° C. and a screw speed of 300 r / min; air-cooling the strands and pelletizing the strands to obtain pellets of the fully degradable polymer composite material.

[0074] Example 5

[0075] A fully biodegradable polymer composite material for tableware comprises the following raw materials in parts by mass: 5 parts of amylose corn starch, 10 parts of hydrophobically modified corn starch, 15 parts of acetylated distarch phosphate of cassava, 30 parts of polylactic acid-polybutylene succinate interpenetrating network structure material, 10 parts of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), 3 parts of polycaprolactone, 2 parts of stearic acid-modified micronized titanium dioxide, 2 parts of chitosan quaternary ammonium salt, 8 parts of a composite plasticizer, 3 parts of a composite thermal stabilizer and 1 part of stearic acid.

[0076] The preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material includes: uniformly mixing the polylactic acid, polybutylene succinate and rosmarinic acid at 80°C according to the mass ratio of polylactic acid to polybutylene succinate of 1:1 and the amount of rosmarinic acid of 5% of the total mass of the polylactic acid and polybutylene succinate; then extruding the materials through a twin-screw extruder at an extrusion temperature of 180°C and a screw speed of 250 r / min; fully melting and mixing the materials under the high temperature and shearing action of the screw to form an interpenetrating network structure; and air-cooling the strips and pelletizing them to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

[0077] Among them, the preparation method of stearic acid-modified micron titanium dioxide includes: dissolving stearic acid in 65°C ethanol with a mass ratio of micron titanium dioxide to stearic acid of 10:1.5, then adding micron titanium dioxide, uniformly dispersing by 30KHz ultrasound, stirring at 500r / min for 1h, evaporating and recovering ethanol, vacuum drying the solid at 50°C to constant weight, and breaking up to obtain stearic acid-modified micron titanium dioxide.

[0078] The composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxy soybean oil of 3:1.5.

[0079] Among them, the composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of 2:1.5.

[0080] The method for preparing the above-mentioned fully degradable polymer composite material for tableware comprises the following steps:

[0081] The amylose corn starch, hydrophobically modified corn starch and acetylated distarch phosphate of cassava were pre-dried at 70°C for 24 hours and set aside; the polylactic acid-polybutylene succinate interpenetrating network structure material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt were pre-crushed and pre-dried at 70°C for 24 hours and set aside;

[0082] S1: uniformly mixing amylose corn starch, hydrophobically modified corn starch, and acetylated cassava distarch phosphate at 70° C. according to parts by mass, then adding stearic acid-modified micronized titanium dioxide and uniformly mixing; then adding polylactic acid-polybutylene succinate interpenetrating network structural material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt and uniformly mixing; then adding a composite plasticizer, a composite thermal stabilizer, and stearic acid, and uniformly mixing at 70° C. to obtain a base material;

[0083] S2: adding the base material into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 160° C. and a screw speed of 300 r / min; air-cooling the strands and pelletizing the strands to obtain pellets of the fully degradable polymer composite material.

[0084] In the above examples, the average molecular weight of amylose corn starch was 160,000 and was sourced from Hubei Langbowan Biopharmaceutical Co., Ltd. Hydrophobically modified corn starch was sourced from Guangzhou Jiexin Chemical Co., Ltd., model 0301, with a particle size of 200 mesh or less. Cassava acetylated distarch phosphate was sourced from Weifang Senrui Biotechnology Co., Ltd. Copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate was sourced from Dongguan Jiatianxia Plastic Materials Co., Ltd., model YU-3824. Chitosan quaternary ammonium salt was sourced from Xi'an Dongchi Biotechnology Co., Ltd., model HACC-102. Stearic acid was sourced from Guangzhou Suixin Chemical Co., Ltd. Polycaprolactone was sourced from Jinan Zhongrui Chemical Co., Ltd., model ZR36. Polylactic acid was sourced from Foshan Guangzheng Chemical Co., Ltd., model FB-01. Polybutylene succinate was sourced from Dongguan Yuefa Plastic Materials Co., Ltd., model FZ92. Rosmarinic acid was sourced from Shaanxi Linzhou Biotechnology Co., Ltd., model LZ-MDXS. Micronized titanium dioxide was sourced from Zhuyu New Materials Technology Co., Ltd., model ZY-G20, with a 460 mesh sieve. Tributyl citrate was sourced from Jiyang Hongfa Chemical in Jinan. Epoxidized soybean oil was sourced from Guangzhou Runquan Chemical Co., Ltd.; ferric pyrophosphate was sourced from Wuhan Baixing Biotechnology Co., Ltd.; and zinc stearate was sourced from Dongguan Shanyi Plastics Co., Ltd.

[0085] Comparative Example 1

[0086] In the fully degradable polymer composite material, the amylose corn starch was replaced by hydrophobically modified corn starch; other parameters and methods were the same as in Example 1.

[0087] Comparative Example 2

[0088] In the fully degradable polymer composite material, acetylated cassava distarch phosphate was replaced by hydrophobically modified corn starch; other parameters and methods were the same as in Example 1.

[0089] Comparative Example 3

[0090] In the fully degradable polymer composite material, both the amylose corn starch and the acetylated cassava distarch phosphate were replaced by hydrophobically modified corn starch; other parameters and methods were the same as in Example 1.

[0091] Comparative Example 4

[0092] In the preparation method of the polylactic acid-polybutylene succinate interpenetrating network structural material, no rosmarinic acid is added; other parameters and methods are the same as in Example 1.

[0093] Comparative Example 5

[0094] In the fully degradable polymer composite material, the number of added polylactic acid-polybutylene succinate interpenetrating network structural materials was reduced from 35 parts to 15 parts, and the remaining 20 parts were replaced by a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate; other parameters and methods were the same as in Example 1.

[0095] Comparative Example 6

[0096] In the fully degradable polymer composite material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate is replaced by a polylactic acid-polybutylene succinate interpenetrating network structure material; other parameters and methods are the same as in Example 1.

[0097] Comparative Example 7

[0098] No polycaprolactone was added to the fully degradable polymer composite material; other parameters and methods were the same as in Example 1.

[0099] Comparative Example 8

[0100] The stearic acid-modified micron titanium dioxide was replaced by micron titanium dioxide without modification; other parameters and methods were the same as in Example 1.

[0101] Comparative Example 9

[0102] Ferric pyrophosphate was used throughout the composite thermal stabilizer; other parameters and methods were the same as in Example 1.

[0103] Comparative Example 10

[0104] Among the composite heat stabilizers, zinc stearate was used throughout; other parameters and methods were the same as in Example 1.

[0105] Comparative Example 11

[0106] Among the composite plasticizers, tributyl citrate was used throughout; other parameters and methods were the same as in Example 1.

[0107] Comparative Example 12

[0108] All composite plasticizers used were epoxidized soybean oil; other parameters and methods were the same as those in Example 1.

[0109] The performance of the materials prepared in the above embodiments and comparative examples was tested; the injection temperature of the samples was 170° C. and the holding pressure was 80 MPa.

[0110] 1. Tensile Strength Test: Tests were conducted in accordance with GB / T 1040.2, "Plastics—Determination of Tensile Properties—Part 2: Test Conditions for Molded and Extruded Plastics." The total length of the specimen was controlled at 150 mm, with a gauge length of 50 mm, a width of 10 mm, and a thickness of 4 mm. Five parallel specimens were prepared for each group. Tensile tests were conducted using a universal testing machine. When the specimen broke, the maximum load was recorded, and the tensile strength was calculated. The average test results are shown in Table 1 below.

[0111] 2. Flexural Strength Test: Tests were conducted in accordance with GB / T 9341, "Plastics - Determination of Flexural Properties." The specimens were set to 80 mm in length, 10 mm in width, and 4 mm in thickness. Five parallel specimens were prepared for each group. Flexural tests were conducted using a universal testing machine. When the specimen failed, the maximum load was recorded, and the flexural strength was calculated. The average test results are shown in Table 1 below.

[0112] 3. Heat deformation temperature test: Refer to GB / T 1634.2 "Determination of load deformation temperature of plastics Part 2: Plastics, hard rubber and long fiber reinforced composite materials" for testing. Prepare specimens with a size of 120mm×15mm×4mm, and prepare 3 parallel specimens for each group. Use a heat deformation Vicat softening point temperature tester for testing. Place the specimen on the heating table of the instrument, apply a load of 1.8MPa, and heat the specimen evenly at a heating rate of 120℃ / h. During the heating process, the bending deformation of the specimen is monitored in real time by the high-precision displacement sensor of the instrument. When the bending deformation of the specimen reaches 0.21mm, record the temperature at this time, which is the heat deformation temperature. The average test results are shown in Table 1 below.

[0113] IV. Water Absorption Test: The material was processed into thin sheets measuring 50 mm × 50 mm × 4 mm, with five replicates prepared for each group. First, the samples were dried in a 105°C oven to a constant weight, and the mass, m0, was recorded. Next, the dried samples were completely immersed in 25°C distilled water for 24 hours. After removal, the surface moisture was gently blotted with filter paper, and the samples were immediately weighed, with the mass, m1, recorded. Water Absorption = (m1 - m0) ÷ m0 × 100%. The average test results are shown in Table 1 below.

[0114] 5. Degradation rate test: The material was made into a circular sheet with a diameter of 50 mm and a thickness of 2 mm, weighed, and recorded as M0. Five parallel samples were prepared for each group. Soil rich in microorganisms was selected, and the soil moisture was adjusted and maintained at 60%, and the temperature was controlled at 30°C to simulate natural environmental conditions. The samples were buried in the soil, taken out every 30 days, washed, and then placed in a 60°C oven to dry to constant weight and weighed, and the mass M1 was recorded. Degradation rate = (M0-M1) ÷ M0 × 100%; the detection period was set to 180 days. The average test results are shown in Table 1 below.

[0115] Table 1 Test results

[0116]

[0117]

[0118] From the above results, it can be seen that the materials of Examples 1 to 5 have good performance, better tensile strength and bending strength, better mechanical strength, are not easy to be brittle, have good heat and water resistance, and are more conducive to rapid degradation.

[0119] From the results of Comparative Example 1, it can be seen that the amylose corn starch molecules have a linear structure and a certain degree of crystallinity. In the material system, they can provide rigid support like a "skeleton", enhancing the tensile and bending strength of the material. When the amylose corn starch is replaced with the hydrophobically modified corn starch, the molecular structure of the hydrophobically modified corn starch changes, and its rigidity is lower than that of the amylose corn starch, resulting in a decrease in the overall rigidity of the material. The crystalline structure of the amylose corn starch has a positive effect on the thermal stability of the material. After the replacement, the internal crystalline structure of the material changes, and the thermal deformation temperature decreases. In addition, the hydrophilicity of the hydrophobically modified corn starch is different from that of the amylose corn starch. When preparing the material, the molecular bonding structure is different, and the water absorption changes. In terms of degradation, due to the change in starch structure, the site and method of action of microorganisms on the material change, resulting in a decrease in the degradation rate.

[0120] The results of Comparative Example 2 show that acetylated distarch phosphate from cassava contains unique chemical groups that interact with other material components to form a relatively compact structure, significantly contributing to the material's mechanical properties. When replaced with hydrophobically modified corn starch, these interactions within the material weaken, resulting in a decrease in overall mechanical properties. The unique structure of acetylated distarch phosphate from cassava helps improve the material's thermal stability, resulting in a decrease in heat distortion temperature after replacement. During the degradation process, changes in the starch structure alter the ease or difficulty of microbial action, resulting in a change in degradation rate.

[0121] The results of Comparative Example 3 show that the simultaneous replacement of amylose corn starch and acetylated distarch phosphate from tapioca starch fundamentally alters the structure and properties of the starch portion of the material, significantly damaging the structural integrity of the material. The rigid support and interaction network originally provided by amylose corn starch and acetylated distarch phosphate from tapioca starch are disrupted, resulting in a significant decrease in mechanical properties. The heat deformation temperature is also significantly reduced due to the instability of the material's internal structure. The water absorption rate increases significantly due to the change in hydrophilicity caused by the altered starch structure, and the degradation rate is also significantly reduced.

[0122] As can be known from the result of Comparative Examples 4: rosmarinic acid plays a key role in the poly(lactic acid)-poly(butylene succinate) interpenetrating network structure material preparation process. It can promote the cross-linking reaction between poly(lactic acid) and poly(butylene succinate) molecules, makes formation more closely connected between the molecular chain, strengthens the compatibility between the two polymers simultaneously, allows them to work together better, also has antioxidant effect, prevents poly(lactic acid) and poly(butylene succinate) from being oxidized at high temperature. When not adding rosmarinic acid, the interpenetrating network structure is imperfect, and the intermolecular force weakens, and the material, when being stretched and bent by external force, easily slides relative to and separates in the molecular chain, causes tensile strength and flexural strength to reduce. Heat distortion temperature also reduces because of the weakening of intermolecular interaction.

[0123] As shown in the results of Comparative Example 5 (the amount of polylactic acid-polybutylene succinate interpenetrating network structure material added is reduced), the polylactic acid-polybutylene succinate interpenetrating network structure material has higher strength and good thermal stability, and contributes more to mechanical properties and thermal properties in the material system. When its addition is reduced to 15 parts from 35 parts, the remainder is replaced by a copolymer of 20 parts of 3-hydroxybutyrate and 3-hydroxyvalerate, because the copolymer performance of 3-hydroxybutyrate and 3-hydroxyvalerate is different from that of the polylactic acid-polybutylene succinate interpenetrating network structure material, the combined synergistic effect is insufficient, and its strength and thermal stability are relatively low. This makes the carrying capacity of the entire material decline, and tensile strength and flexural strength decrease. The heat deformation temperature is also reduced due to the reduction of the heat-resistant component in the material, combined with structural changes. In terms of water absorption and degradation rate, due to the change in the overall composition structure of the material, the interaction between the material and water and the effect of microorganisms on the material change.

[0124] The results of Comparative Example 6 (replacing the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate) show that the molecular structure and performance characteristics of the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate differ from those of the polylactic acid-polybutylene succinate interpenetrating network material. The substitution alters the material's molecular chain structure and aggregate structure, resulting in changes in various properties.

[0125] The results of Comparative Example 7 (without polycaprolactone) show that polycaprolactone has good flexibility and toughening effects, which can improve the processing properties and toughness of the material in the material system. When polycaprolactone is not added, the toughness of the material decreases. When subjected to tensile and bending external forces, the stress concentration phenomenon within the material is more obvious, making brittle fracture more likely. As a result, the tensile strength and flexural strength decrease slightly, but the heat distortion temperature, water absorption rate, and degradation rate are less affected.

[0126] As can be seen from the result of Comparative Example 8 (unmodified micron titanium dioxide): stearic acid modified micron titanium dioxide improves the compatibility and dispersibility between micron titanium dioxide and the matrix material through the effect of stearic acid. When replacing stearic acid modified micron titanium dioxide with unmodified micron titanium dioxide, unmodified micron titanium dioxide easily reunites in the matrix and can not be evenly dispersed in the material, and also just can't effectively transfer the performance of stress and reinforced material. This causes the material to be subjected to external force, and stress can not be evenly distributed, and easily produces stress concentration around the reunited micron titanium dioxide particles, thereby reducing tensile strength, flexural strength, and thermal deformation temperature. In the degradation process, due to the change of the dispersed state of micron titanium dioxide, the degradation process of the material has also been produced to a certain extent.

[0127] The results of Comparative Example 9 show that the ferric pyrophosphate and zinc stearate in the composite thermal stabilizer work together in a specific ratio to exert a thermal stabilizing effect. Ferric pyrophosphate can capture the free radicals generated by the material during the heating process and inhibit the thermal degradation reaction; zinc stearate can stabilize the chemical structure of the material by reacting with the acidic substances in the material. When all ferric pyrophosphate is used, although it can inhibit the generation of free radicals to a certain extent, the reaction between zinc stearate and acidic substances is lost, the stability of the chemical structure of the material decreases during the heating process, and thermal degradation and structural changes are more likely to occur, and the mechanical properties are also affected.

[0128] From the results of Comparative Example 10, it can be seen that: Similarly, when zinc stearate is used entirely, although it can stabilize the chemical structure of the material to a certain extent, it cannot effectively inhibit the generation of free radicals. When the material is heated, the thermal degradation reaction caused by free radicals is intensified, the thermal stability deteriorates, and the mechanical properties also decrease accordingly.

[0129] The results of Comparative Example 11 show that tributyl citrate and epoxidized soybean oil in the composite plasticizer act as a plasticizer in specific proportions. Tributyl citrate and epoxidized soybean oil molecules can intercalate between polymer chains, weakening the interactions between the chains and imparting improved flexibility and processing properties to the material. However, when tributyl citrate is used exclusively, its sole action fails to achieve the optimal plasticizing effect, resulting in reduced flexibility and processing properties. This restricts the sliding between the molecular chains when the material is subjected to external forces, and also affects the heat distortion temperature to a certain extent.

[0130] The results of Comparative Example 12 show that the optimal plasticizing effect cannot be achieved when epoxy soybean oil is used alone. When epoxy soybean oil is used alone, it cannot completely weaken the interaction between polymer molecular chains like a composite plasticizer, resulting in a decrease in material performance.

Claims

1. A fully degradable polymer composite material for tableware, characterized in that: The invention comprises the following raw materials in parts by weight: 3 to 5 parts of amylose corn starch, 10 to 15 parts of hydrophobically modified corn starch, 10 to 15 parts of acetylated distarch phosphate of cassava, 30 to 40 parts of polylactic acid-polybutylene succinate interpenetrating network structural material, 8 to 10 parts of copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, 3 to 5 parts of polycaprolactone, 1 to 2 parts of stearic acid modified micronized titanium dioxide, 2 to 4 parts of chitosan quaternary ammonium salt, 5 to 8 parts of composite plasticizer, 3 to 5 parts of composite heat stabilizer and 0.3 to 1 part of stearic acid; The polylactic acid-polybutylene succinate interpenetrating network structure material is prepared from polylactic acid, polybutylene succinate and rosmarinic acid; the amount of rosmarinic acid used is 3% to 5% of the total mass of polylactic acid and polybutylene succinate; The composite plasticizer is a composite plasticizer with a mass ratio of tributyl citrate to epoxidized soybean oil of (3-4): (1-1.5); The composite heat stabilizer is a composite plasticizer with a mass ratio of ferric pyrophosphate to zinc stearate of (2-3): (1-1.5).

2. A fully biodegradable polymer composite material for tableware according to claim 1, characterized in that: The preparation method of the polylactic acid-polybutylene succinate interpenetrating network structure material comprises: uniformly mixing polylactic acid, polybutylene succinate and rosmarinic acid at 80° C. to 90° C., then extruding through a twin-screw extruder, air-cooling and drawing, and pelletizing to obtain the polylactic acid-polybutylene succinate interpenetrating network structure material.

3. A fully degradable polymer composite material for tableware according to claim 2, characterized in that: The mass ratio of polylactic acid to polybutylene succinate is (1-1.5):1; the amount of rosmarinic acid is 3%-5% of the total mass of polylactic acid and polybutylene succinate; the extrusion temperature of the twin-screw extruder is 165°C-180°C, and the screw speed is 250r / min-300r / min.

4. A fully biodegradable polymer composite material for tableware according to claim 1, characterized in that: The preparation method of stearic acid modified micron titanium dioxide includes: dissolving stearic acid in ethanol, then adding micron titanium dioxide, uniformly dispersing by ultrasonication, stirring for reaction, evaporating and recovering ethanol, vacuum drying and breaking up the solid to obtain stearic acid modified micron titanium dioxide.

5. A fully biodegradable polymer composite material for tableware according to claim 4, characterized in that: The mass ratio of micron titanium dioxide to stearic acid is 10:(1-1.5); the amount of ethanol used is 100 to 150 times the mass of stearic acid, and the temperature of ethanol is 60°C to 65°C; the stirring reaction time is 1 hour to 2 hours, and the stirring reaction speed is 300 r / min to 500 r / min; the vacuum drying temperature is 40°C to 50°C, and the vacuum drying is carried out to constant weight.

6. A method for preparing a fully degradable polymer composite material for tableware, for preparing the fully degradable polymer composite material for tableware according to claim 1, characterized in that: The preparation method comprises the following steps: S1: uniformly mixing amylose corn starch, hydrophobically modified corn starch, and acetylated cassava distarch phosphate at 70°C to 80°C according to their weight ratios, then adding stearic acid-modified micronized titanium dioxide and uniformly mixing; then adding polylactic acid-polybutylene succinate interpenetrating network structural material, copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone, and chitosan quaternary ammonium salt and uniformly mixing; then adding a composite plasticizer, a composite thermal stabilizer, and stearic acid and uniformly mixing at 60°C to 70°C to obtain a base material; S2: adding the base material into a twin-screw extruder for melt blending and extrusion, air cooling and drawing, and pelletizing to obtain pellets of a fully degradable polymer composite material.

7. The method for preparing a fully degradable polymer composite material for tableware according to claim 6, characterized in that: The linear corn starch, hydrophobically modified corn starch and acetylated cassava distarch phosphate are pre-dried; the polylactic acid-polybutylene succinate interpenetrating network structural material, the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, polycaprolactone and chitosan quaternary ammonium salt are pre-crushed and dried.

8. The method for preparing a fully degradable polymer composite material for tableware according to claim 6, characterized in that: The extrusion temperature of the twin-screw extruder is 160° C. to 170° C., and the screw speed is 250 r / min to 300 r / min.

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